饱和土体中空沟对移动荷载被动隔振的2.5D边界元法分析

Analysis of effectiveness of passive isolation for vibration due to moving loads on saturated soil by using open trench with 2.5D boundary element method

根据饱和土Biot理论及移动荷载特性,采用积分变换方法,推导了半无限饱和土体频域-波数内的边界积分方程,讨论了2.5D边界积分方程中Cauchy的奇异性,并分析了空沟对移动荷载引起饱和土体振动的被动隔振效果。通过与已知文献结果比较,验证了算法的正确性。数值结果表明,采用2.5D BEM不仅可以解决具有复杂表面的移动荷载作用下动力响应问题,而且可极大减小计算工作量。对于饱和土体受高速移动荷载作用,空沟更能有效减小土体孔压、竖向位移的振幅;当荷载速度较小时,空沟对土体表面的水平向位移几乎不起衰减作用,甚至有放大效应。另外,随空沟距振源的距离增大,空沟能够更好阻隔土体表面波传播。

Based on Biot＇s theory and considering the property of moving loads, the boundary integral equations in the frequency domainwave number for semiinfinite saturated soil is obtained by using the integral transform methods. The Cauchy type singularity of the 2.5D boundary integral equation is discussed and the effectiveness of passive vibration isolation using the open trench on the saturated soil is analyzed. Comparing the result with an existing one shows a good agreement. Numerical results show that, the present 2.5D boundary element method （BEM） is not only adaptable to solve the dynamic responses of moving loads with complicated boundary conditions, but also the computation time can be decreased greatly. For moving loads with high velocity, a considerable oscillation reduction of the pore pressure and the vertical displacement can be achieved by using open trench. The open trench barrier has no effect on the horizontal displacement for moving loads with lower velocity, even has the amplificatory effect on the vibration. Moreover, with the increasing of the distance between the vibration source and the open trench, the isolation effect of the surface wave propagation may be improved.